A good chimney draft is needed to ensure that a stove or fireplace is producing heat or fire optimally. When you have sufficient draft, you don’t need to use so much wood or other like materials to create and sustain fire and heat, thus saving you money and resources. On the other hand, if you have poor draft you would have to feed your fireplace or stove firewood constantly to maintain the required amount of fire or heat.
Nature of Air Movement in a Chimney
As a rule hot air rises up and cold air tends to move downwards. A fireplace or stove when in use produces smoke that is made up of hot air. This hot air naturally makes its way up to the chimney and out into the atmosphere. As this happens, air is sucked into the fireplace or stove simultaneously. This is called draft. It compensates for the escaping air that also fans the flames making it bigger and more intense.
Draft Regulation Options
Regulating draft is important to ensure that sufficient air is pulled to maintain fire, and for smoke to exit harmlessly into the atmosphere. This can be achieved by building well-designed chimney structures.
A flue is the chamber through which smoke from the fireplace or stove passes through and eventually exits out into the atmosphere. It is recommended that flue size be at least 25 percent bigger than the tube that connects the stove or pipe to the chimney. This is to ensure efficiency in the travel of smoke through the flue and out of the chimney.
With respect to shape, circular flues offer the least friction to smoke rising up through the chimneys; thus, this circular type is the most efficient in terms of design. The lining of flues should also be as smooth as possible to facilitate the passage of smoke.
For optimum efficiency, chimneys should be located as close as allowable to stoves or fireplaces. With stove units, it is recommended that pipes connecting the chimneys to stoves should be no longer than 10 feet.
As a rule, the longer the chimney the better regulated the draft. It is also easier to lessen the draft in a tall chimney than increase draft in a short chimney.
The more bends you have in a chimney, the less the draft that gets produced or generated. So if draft regulation is to be considered, it is recommended that one reduces the number of bends in a chimney as possible.
Too wide a chimney can cause problems with draft since it will allow rising smoke to cool prematurely. A chimney’s diameter should be similar to a flue’s diameter to ensure efficient smoke passage. In cases where you have wide chimneys, you can use a smaller diameter flue to compensate for the oversize.
A chimney that is well-constructed and well-designed can save owners money in the long run. A good chimney draft is necessary to ensure that fireplaces or wood-fired stoves run optimally and produce adequate heat.